Re: Queued Writes vs. MTU
Re: Queued Writes vs. MTU
- Subject: Re: Queued Writes vs. MTU
- From: Matthias Ringwald via Bluetooth-dev <email@hidden>
- Date: Sun, 30 Oct 2022 17:01:12 +0100
Hi Mickey
Is there are reason for write commands longer than 247 bytes? The over-the-air
packets cannot be bigger anyway, so there's not much throughput improvement.
Could you post a PacketLogger trace to check the ATT PDUs?
How did you get the max write size? CBPeripheral:maximumWriteValueLength with
both write types?
Best
Matthias
> On 28 Oct 2022, at 15:42, Dr. Michael 'Mickey' Lauer via Bluetooth-dev
> <email@hidden> wrote:
>
> I have a problem with a BLE peripheral and iOS.
> It’s unclear who is to blame, but one (or both) are doing something bogus.
>
> Let’s assume I only want to do WriteWithResponse in order to have
> better diagnostics (delegate being called after transmit).
>
> When I ask iOS for the WriteWithResponse MTU, it returns 512.
> Sending packets up to 247 data bytes works fine (which, by the way, is
> what iOS reports for WriteWithoutResponse), but once I
> exceed this, iOS sends a PREPARE WRITE to my peripheral, which –
> due to that peripheral not implementing queued writes – is not answered
> and the whole transfer stalls.
>
> Unfortunately it is an off-the-shelf BLE device (OBDLink CX OBD2 adapter),
> where I don’t have any control over the stack it’s using.
>
> Could anyone share some light on this? Let’s start by the question
> why iOS claims 512 to be an OK MTU for that peripheral?
>
> Best regards,
>
> Mickey.
> _______________________________________________
> Do not post admin requests to the list. They will be ignored.
> Bluetooth-dev mailing list (email@hidden)
> Help/Unsubscribe/Update your Subscription:
>
> This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Bluetooth-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden